A Biomimetic Fishdriven By Dielectric Elastomers:Design And Experiments

Compared to underwater robot driven by propeller propulsion,biomimetic fish has better maneuverability because of the driving by artificial fish fins.Moreover,the shape of a biomimetic fish is similar to that of a natural fish,so it has better stealth ability in the line of duty.Compared to the traditional biomimetic fish fin driven by motor,the soft fish fins driven by smart material have advantages in simulating movements of a natural fish that give the biomimetic fish better swimming performance.In addition,the biomimetic soft fish fins is an applicable experimental model for research on the actuation principle of natural fish.In this paper,a biomimetic fish driven by dielectric elastomer is fabricated.Compared to the biomimetic fish driven by other smart material,the robot fish driven by dielectric elastomer demonstrates better performance in swimming speed.Specific contents are as follows:Firstly,based on the comprehensive analysis and comparison with various propulsion methods of natural fish,the pattern with central fin is selected as the propulsion scheme of the biomimetic fish and the straight walking mechanism of the biomimetic fish by pectoral fin propulsion is analyzed.Moreover,the oscillation mode of the pectoral fin is designed,and the biomimetic pectoral fin is fabricated by a dielectric elastomer minimum energy structure.The working environment of bionic fish is underwater and dielectric elastomer materials require a high voltage to drive the fish fins.Therefore,insulation of the high voltage is very important to the stability of the biomimetic fish.In this design,704 silicon rubbers is chosen as insulation materials and the structure of double layer sandwich is chosen as driving scheme,in addition,environmental liquid is chosen as negative electrode,thus the stability of the biomimetic fish is greatly improved.Secondly,when the biomimetic fish is swimming,the environmental flow field is complex and difficult to establish analytic model.So the hydrodynamic simulation of the biomimetic fish is performed by using FLUENT powerful software and the flow field is analyzed.The variations of flow pressure with the fin flutter and the evolution of eddy field are analyzed quantitatively.Moreover,the influence of fin angle and frequency of flapping frequency on the propulsion force is analyzed as well,so the maximum velocity with different initial angles and flutter frequencies is obtained.Finally,in order to validate the propulsion scheme and the simulation results based on FLUENT software,some experiments are operated,such as the swimming of the biomimetic fish driven by different voltage waveform,different amplitude and different frequency.Experimental results demonstrate that the biomimetic fish can realize straight line cruising with maximum speed of 33mm/s.Therefore,dielectric elastomer is a suitable candidate to drive a soft biomimetic fish,and the propulsion mode based on two pectoral fins is feasible in engineering.